Oil wells and natural gas are generally drilled into the earth and the underground oil or gas deposits are forced to the surface along the well bore by the underground pressure, or, pumped up using one or more pumps (often in a series). The well-bore is drilled from an oil-rig on the surface of earth using a rotating drilling bit. When the rotating drilling bit is driven into the earth, it cuts through layers of soil and rocks using a continuous flow of compressed drilling fluid (also known as “drilling mud”) supplied through a conduit, which can be coiled tubing or a drill string (composed of a contiguous series of pipes). Drilling with coiled tubing necessitates use of a mud motor as part of the bottom hole assembly (“BHA”), for rotating the drilling bit. With a drill string, sometimes a mud motor is not included, as one can rotate the string itself to rotate the bit.
During drilling, hollow metallic tubes (also known as “casings”) are inserted within the drilled bore to prevent the walls of bore from collapsing. In a deep enough bore, multiple hollow casings are installed vertically one above the other by screwing ends of adjacent sections with each other, thus forming a “bore casing.” The well-bore within the bore casings should be kept clean (for proper functioning of tools and equipment), by efficiently removing rock debris, dirt and mud generated by drilling. Mud pumped down from the surface to the BHA, carries debris and dirt from the BHA upwardly inside the well-bore. But the pressurized mud alone may not be adequate to remove sufficient amounts of debris to clean the well-bore and provide a satisfactory operating environment for the tools and equipment therein.
Hence, there's need for a device which more effectively removes drilling debris from the well-bore and the region near the BHA.